Automatic recordfr for transmission efficiency



A. L. MATTE.

June 13, 1933.

AUTOMATIC RECORDER FOR TRANSMISSION EFFICIENCY Filed Dec. 18, 1930 2 Sheets-Sheet 1 l l ksumnu n d gmw 3g sgww lNVENTOR fll We ATTORNEY June 13, 1933. -A. L..-,-MATTE 1,913,496

AUTOMATIC RECORDER ECR TRANSMISSION EFFICIENCY Filed Dec. 18. 1950 2 Sheets-Sheet 2 ATTORNEY Patented June 13, 1933 rrED STATES ANDREW L. MATTE, E SUMMIT, NEW 'JEEsEY, Assrcnon To AMERICAN TELEPHONE rnnnsnnrn COMPANY, a conronarron oENEw YORK AUTGMATIC F012. TRANSBIISSION EFFICIENCY This invention relates to a system for automatically determining and recording the transmission efficiency of a circuit, and particularly to a system in which such transmission efficiency is measured at each of a plurality of frequencies, which frequencies are transmitted simultaneously over the sald circuit.

In the copcnding application of A. L. Matte, Serial No. 503,3421, filed Dec. 18, 1930, there is described a system for indicating and also for recording manually the transmission efficiency of a circuit at each of a plurality of frequencies during the simultaneoustransmission of all of the measuring frequencies. As pointed out in detail in that application, the transmission efficiency of a circuit made up solely of resistances and free from external interference, when measured at a single frequency, would be the same regardless of whether that frequency were the only one present in the system or was one of a plurality of frequencies simultaneously present. That equality does not exist in the case of long transmission lines, particularly where relatively high energy'levels are used, because overloading and modulation effects take place. Those phenomena produce parasitic currents that introduce an error in the meas urement of the transmission efficiency at a single frequency.

In the said copending application there have been described several arrangements by which the error caused by those parasitic currents maybe eliminated. Those arrange ments produce either a visual indication or a graphic record of such cfiiciency by manual operation. 7 y

The present invention resides in an arrangement for automatically recording on a suitably printed chart the transmission efiiciency of a circuit at each of a plurality of frequencies during the simultaneous transmission of all of such frequencies.

Other objects of tie invention will be apparent from the following'description, when read in connection with the attached draW ings, of which Figure 1 is a circuit diagram showing schematically one form of embodiment of the invention; Fig. 2 shows certain Application filed December 18, 1930 Serial No. 503,342.

of the mechanical features of the arrangement shown'in Fig. l; and Fig. 3 is a detail of a ratchet employed in the arrangements of the other figures. 1

In'Fig. 1,.G G and G at the west station represent sources of current of diiferent frequencies that are employed in determining the transmission efficiency of a circuit. While only three generators are shown, it is to be understood that the number of frequencies may be greater or less than three, and that any well known source or sources of current may be employed. The generators are connected by the transformers T T and T with the potentiometers P P and P respectively. The potentiometers are adapted to be connected by the switches Si, S and S with the input side of the vacuum tube V that acts as a voltage adder.

The output of that tube is connected by the transformer T with the switch S which, when thrown inward, connects the output circuit with the measuring apparatus, and when thrown outward, impresses the output voltage upon the circuit L The arrangement just described is similar to that shown in Fig. 1 of the copending application. Plug 4 of the cord 5 is adapted to be inserted in the jacks J in order to connect the output of the generating system just described with the input of the amplifier RA when the plug 6 is inserted in the jack J As pointed out in the copending application, those acks are strapped together by the cord 5 during the process of calibrating the measuring apparatus, but that such cord is removed during the transmission of the testing currents over the circuit L whose efficiency is to be measured by the apparatus at the left hand side of the figure.

A similar group of generators G G and G shown at the east station at the righthand side .of Fig. 1, produce currents of the same frequencies as generators G1, G and G The generators G and G3 are connected by the transformers T T and T with the potentiometers P P and P The latter are connected by their associated switches with the vacuum tube V thatfunctlons as a voltage adder. The output of that the'measurement by such perforation.

tube is connected with the switch S so that the current may be applied either to the circuit L or to the thermocouple TC and its associated milliammeter A The current transmitted by L will be impressed upon the amplifier EA whose output is connected with the branch circuits each of which contains one of the filters F F and F As sociated with the filters are the potentiometers P P and P that may be adjusted once for all to calibrate the apparatus prior to the making of the measurements of transmission efiiciency of the circuits such as L The voltages across the potentiometers will be impressed upon the line detector D by the operation of the sequence switches S S 2, and S The lower contact of each of the group of contacts controlled by tl e sequence switches controls one of the linkage magnets M M and M whose function is to control the fingers connected with their armatures, which fingers, as shown in Fig. 2, enable the hammer 16 to force the pins through the recording paper and thus produce a record of The rectified current of the line detector D passes through the right-hand winding of the differential galvanometer DG The left-hand winding of that galvanometer is connected with the output of the calibrating detector D which is connected with the potentiometer P The calibrating current is derived, for purposes of illustration from the source shown at the left-hand side of the figure, one of the frequencies being selected by the filter F and impressed upon the potentiometer P The movable arm of R is connected with the shaft 5 with which is also connected the gear 6 that is rotated by the ratchet 7. The movement of the latter is controlled by the ratchet magnet lVL. The shaft 5 is connected by the gear and pinion 8 with a shaft 9 that controls the sequence switch S and the other sequence switches previously mentioned. The shaft 5 also drives the recording drum 12, as shown in Fig. 2. The sequence switch S through its contacts C controls the disconnection of the battery lB from certain of the relays of the system after a cycle of operations has been completed. The push button 10 is used to start the cycle of operations. The closing of its contact connects the battery B with the ratchet magnet M. and causes the rotation of the gear 6. The ratchet relay R when operated, effects the energization of the printing magnet M B is the printing magnet release relay whose function is to release the printing magnet upon the completion of the making of the record; and R is the locking relay that serves to prevent a second operation of the recording device at the same test ing frequency, until the completion of a testing cycle.

The manner in which the system is calibrated is as follows: Let it be assumed that will the generators G G and G are operating and that the potentiometers P P and P have been adjusted so that a predetermined voltage at each frequency is impressed upon the tube V The manner of making that adjustment is fully described in the said copending application. The output current of the said tube flows partly through the circuit that leads to the filter F One of the fre quencies will be transi'nitted through the filter and will be impressed across the potentiometer P The transformer T is always connected through the switch S to a circuit having an impedance equal to that of the circuit to be measured. The current that passes F be rectified by D and impressed upon the left-hand winding of the differential galvanometer DG which, in this particular embodiment, is essentially a sensitive relay, the tongue of which will remain on either contact whenever the current through its two windings are equal, and will move over from one contact to the other when the currents differ by an amount which is negligibly small compared with the accuracy desired in the measurements.

The plugs 4. and 6 are then inserted in the jacl-zs J and J and the switch S is thrown to connect the output of the tube V with the input of the amplifier HA he current of all frequencies, as amplified by HA will be impressed upon the branched output circuit and the several frequencies will be selected by the filters and the voltages'of the several frequencies will be impressed across the respective fixed potentiometers P P and P With only one of the received frequencies impressed at a time on D (depending on the position of shaft 9), and P in the position corresponding to Zero equivalent on the chart, each of the fixed potentiometers, P P etc., is adjusted till the tongue of DG just leaves its left-hand contact and moves over to the grounded or right-hand contact. The desired adjustments of the shafts may be made by rotating the drum 12 by hand.

After the automatic measuring and recording apparatus has been calibrated in the manner just described, it is ready for measuring the transmission efficiency of the circuit L The generators G and G are effec tively connected with the said circuit after their potentiometers have been adjusted to apply known amounts of voltage to the adding tube V The plugs 4 and 6 of the cord 5 are removed from the acks J and J respectively. The latter disconnection effectively connects the circuit L with the input of the amplifier RAJ so that the currents of the various frequencies transmitted over that circuit will be amplified and impressed upon the va ious branches containing the networks, each selective of one of the frequencies transmitted.

It will be assumed that a chart 11 has been placed upon the drum 12 of the arrangement shown in Fig. 2, and furthermore assumed that the switch S is in such position that its contact G is open. Under these conditions the whole mechanism is at a stand still. P is in such a position that the input to D is shorted and the. galvanometer DGr is on its left-hand contact; the drum 12 is also so placed that the end of the chart corresponding to the minimum measure'able equivalent is about to pass over the pin 17. The button is pushed, thereby connecting the battery B with a circuit that includes the left-hand contact of relay R the magnet M the ratchet 7 and its contact 13 which is grounded. The flow of current through M attracts the ratchet and causes the rotation of the gear 6 in the direction indicated by the arrow. As soon as the gear rotates, the shaft to which it is attached will simultaneously cause therotation of the switch S and also the arm of the potentiometer P The rotation of S raises its arm and closes its contact, thereby continuing the connection of the battery B with the ratchet magnet even though the button 10 may be released. The rotation of the arm of P increases the voltage applied to the detector D and likewise the current flowing through the left-hand winding of DG The ratchet 7 will continue to move up and down and the gear 6 will continue to rotate till the sequence switches reach the position shown in the drawing which represents the condition for the measurement of the frequency that passes the filter F Under the condition shown the contacts C of switch S will be closed. The closing of the upper contact connects the potentiometer with the line de tector D which in turn is connected with the right-hand winding of the galvanometer DG The closing of the lower contact of C permits current to flow from battery B over the said contact and through the magnet M and the resistance 14 to ground. The operation of M causes the movement of the finger 15 so as to bring it between the hammer 16 and the lower end of the pin 17 of the recording device, all of which is clearly shown in Fig. 2. During the closing of the contact C the ratchet 7 will continue to operate and the potentiometer P will be moved around until a point is reached where the current in the left-hand winding overcomes that in the right-hand winding. Thereupon the armature of the galvanometer will move to its right-hand contact which is grounded. Current will thereupon fiow from the battery B through relay R and the right-hand contact of R to ground and will operate relay R That disconnects the battery B from the ratchet magnet M and stops the rotation of the gear 6 and its associated apparatus. The operation of relay R also connects battery B through the right-hand contact of R and the left-hand contact of H with the printing magnet M to ground, causing the operation of the latter. When the printing magnet opcrates, it attracts its armature, which rotates the shaft 18 and causes the hammer 16 to strike the finger 15, forcing the latter to strike the end of the pin 17 and thereby to cause a perforation of the paper chart 11 that is carried by the drum 12. The rotation of the shaft 18 also closes the contacts 19, thereby permitting the flow of current from E through the winding of the release relay R and the locking relay R and resistance 14 to ground. Both of the latter relays are energized and locked up. As will be seen, relay R derives its operating voltage from the drop in potential through resistance 14. The operation of relay R opens the circuit of the printing magnet M thereby permitting its armature to drop back. As

soon as relay R has operated, the opening of its right-hand contact will remove the ground from the ratchet relay R which is established through DG Since the locking relay R operates upon the drop in potential of the current from the battery B through the resistance 14,- the said locking relay will remain operated as long as the sequence 7 switch S maintains the lower contacts C closed. That prevents the operation of relay R and in turn the operation of the printing magnet M thus rendering impossible the operation of the punching apparatus until the frequency has changed. As soon as the relay R releases, R will drop back into its normal unoperated position and the ratchet magnet M will be energized, thus starting the rotation of the gear 6'which will continue steadily until the punching operation is about to occur for the next testing frequency. i

As soon as the cam of the switch S rotates to lift its movable arm and to open C the current will cease flowing through the resistance 14: and relay R will be released. Likewise, the magnet M willbe deenergized and the finger 15 will be withdrawn, for example by a spring (not shown) from the space between the hammer and the lower end of its associated pin. The shaft 9' will continue to rotate and will cause the closing of the contacts G associated with the switch S thus impressing the second testing frequency upon the line detector D The same cycle of operations will occur as described test frequencies. On the other hand, the re-' sistance of the potentiometer P spans an angle "equal to that of the active part of the chart. The recesses of each cam S S etc., correspond to the angles covered by the chart. After all of the frequencies have been r'= corded, the arm of the switch S drops into its recess, thereby opening the cont-act C That brings the apparatus to a standstill by effectively disconnecting battery B i from IL, simultaneously rings a high resistance alarm 21 to call the attendants attention to the fact that the record is complete.

The invention is not limited to the form shown in the figures, but is capable of embodiment in a variety of other forms without departing from the spirit and scope of the appended claims.

What is claimed is:

1. In a system for automatically recording the transmission efliciency of a circuit, the combination with a circuit over which is transmitted a testing current comprising a plurality of frequencies, of means for selecting each frequency, means to rectify andto apply each selected frequency to a diiferential indicating device to which is also applied a measuring current Whose magnitude is con trollable at will, means to automatically adjust the measuring current to have a predetermined ratio to the testing current in the said indicating device, and means to record the transmission efficiency of the circuit for the selected frequency when such ratio is effected.

2. In a system for automatically recording the transmission efficiency of a circuit, the combination with a circuit of a plurality of sources of currents of different frequencies connected with the said circuit, the magnitude of each component frequency being known, means also connected with the said circuit to select each of the said frequencies, a differential relay, a rectifier connected to one of the windings of the said relay, a sequence switch adapted to apply the currents of different frequencies successively and automatically to the said rectifier, another source of known magnitude connected to the other winding of the relay, the said connection including a potentiometer and means to automatically adjust the setting of the potentiometer until the currents in the windings of the relay differ by a predetermined amount, and means to repeat the said automatic adjustment of the potentiometer for each of the other frequencies in succession.

3. The method for automatically recording the transmission efliciency of a circuit which consists in transmitting a plurality of fre quencies over a line and selecting one of the said frequencies, locally generating a plurality of frequencies and selecting one of them, rectifying each selected frequency, automatically adjusting the magnitude of the selected frequency from the local source until the effect of the rectified currents upon a responsive device causes it to change from one contact to another, and automatically recording the transmission efficiency of the said line for the selected frequency.

4. In a system for automatically recording the transmission efficiency of a circuit over which a plurality of currents of known magnitude and frequency are transmitted, the combination with a plurality of branch circuits each having a filter selective of one of the said frequencies, of a plurality of sequence switches each individual to one of the said branch circuits, a gear and ratchet having an operating magnet associated therewith adapted to rotate the said sequence switches, a plurality of rectifiers, a differential galvanometer having each winding connected with one of the said rectifiers, means controlled at will to start the energization of the operating magnet of the said ratchet whereby one of the said selecting switches will connect its branch circuit with the input of one of said rectifiers, a local source of current effectively connected to the relay, the connection including a potentiometer and a rectifier, the said potentiometer being sooperated by the said gear as to vary the magnitude of the current supplied by the local source to its rectifier, the variation continuing until a predetermined difference exists in the said differential galvanometer, and means to automatically stop the rotation of the said gear when the said difference occurs.

5. In a system for automatically recording the transmission efficiency of a circuit over which a plurality of currents of known mag nitude and frequency are transmitted, the combination with means to automatically select each of the said frequencies in succession of means to rectify the selected frequency, a local source of direct current, a differential device upon which both currents are impressed, means to automatically vary the magnitude of the local current until a predetermined difference exists in said indicating device, and means responsive thereupon to automatically record the transmission efficiency of the circuit at the frequency then selected.

6. In a system for automatically recording the transmission efliciency of a circuit over which a plurality of currents of known magnitude and frequency are transmitted, the combination with a drum of a chart carried thereon, means to rotate the said drum, means to set in operation the said rotating means, a plurality of pins each adapted to perforate the said chart to record the transmission en; ciency of the circuit at one of the said frequencies, a plurality of sequence switches and a potentiometer, all driven by the same rotating means, a differential relay upon which are impressed the current from a local source and also the current of each of the testing frequencies in succession, means controlled by the differential relay to stop the rotation of the said drum, and means to operate that pin corresponding to the test frequency then being applied to the said differential relay, whereby the transmission efficiency of a circuit' at that frequency may be'recorded, and means to repeat such recording at all test frequencies successively and automatically.

7. In a system for automatically recording the transmission efficiency of a circuit over which a plurality of currents of known magnitude and frequency are transmitted, the

- combination with a drum of a chart carried thereon, means to rotate the said drum, means to set in operation the said rotating means, a

plurality of pins each adapted to perforate the said chart to record the transmission eificiency of the circuit at one of the said frequencies, a plurality of sequence switches and a potentiometer, all driven by the same rotating means, a differential relay upon which are impressed the current from a local source and also the current of each of the testing frequencies in succession, means controlled by the differential relay to stop the rotation of the said drum, means to operate that pin corresponding to the test frequency then being applied to the said differential relay, and means to prevent the making of more than one measurement at each test frequency during each cycle of a plurality of measurements.

8. In a system for automatically recording the transmission efficiency of a circuit, the

combination with a circuit over which is transmitted a testing current comprising a plurality of frequencies, of means to separatev the frequencies after transmission, a difierential relay, means to selectively apply the separated frequencies singly and in successive order to one winding of the said relay, means to apply to the other winding of said relay a measuring current, means to automatically adjust the magnitude of the measuring current until it overcomes the effect upon the said relay of the testing current of the frequency then selected, means responsive to said relay to stop the adjustment of the measuring current and means to automatically record the transmission efficiency of the testing current of the frequency then selected.

In testimony whereof, I have signed my name to this specification this 17th day of December, 1930.

ANDREW L. MATTE. 

